1. Field of the Invention
The present invention relates to an electric-powered vehicle such as an electric-powered wheelchair.
2. Description of the Related Art
Electric-powered wheelchairs of the related art include a type of wheelchair in which a motor generates an assisting driving force in accordance with an operating force generated when a caregiver pushes or pulls the wheelchair body while holding operation handles. The operating force generated by pushing or pulling the wheelchair body is detected by using a sensor to detect a force applied on the operation handles.
The wheelchair in which the assisting driving force is generated can be moved by the resultant of the operating force generated when the caregiver pushes or pulls the wheelchair body and the assisting driving force. This can reduce the load on the caregiver.
In the vicinity of the operation handles, brake levers are provided. The brake levers are connected to wheel brake mechanisms by control wires. By manually operating the brake levers, wheels can be mechanically braked.
In the electric-powered wheelchair of the related art, the braking force by the brake operation and the assisting driving force may be simultaneously generated.
By way of example, when the caregiver as an operator pushes the electric-powered wheelchair on an upslope, an assisting driving force is generated in accordance with the pushing operating force. The operator may apply the brake if needed while the wheelchair is moving on the upslope. In this case, the assisting driving force by a motor and the braking force by the brake lever are simultaneously generated.
In this case, the assisting driving force is generated against the braking force. This causes an unnecessary current to flow in the motor in the wheelchair, so that efficiency deteriorates.
For the amount of the assisting driving force generated in the wheelchair, the operator must generate a greater braking force, thus increasing the load of the brake operation.
When the operator deactivates the brake operation while the wheelchair is being brought to standstill by the brake, an assisting driving force which is being generated at the time may suddenly move the wheelchair. This causes instability of operation.